What is Lindlar's catalyst?

$A$ salt-producing hydrocarbon among these compounds is

The synthesis of $3$-octyne is achieved by adding a mixture of sodium amide and an alkyne to a bromoalkane. What are these bromoalkane and alkyne?

$CH_3CH_2CH_2I$ $\xrightarrow{alc. KOH} A$ $\xrightarrow{Br_2} B$ $\xrightarrow{NaNH_2 / NH_3} C$. In this reaction,$C$ is:

What is the product obtained from the oxymercuration of $1-butyne$ using $HgSO_4$ and $H_2SO_4$?

The incorrect statement regarding ethyne is